Deep ocean parachute release

ABSTRACT

A drogue chute is used to extend a long line transducer array in the water as it is being towed in or played out in an ocean current. To avoid problems during a subsequent retrieval of the array, the drogue chute is disconnected. For this reason a release mechanism is interposed between the transducer array and the chute. This release mechanism provides for a nonabrupt separation of the array from the chute&#39;&#39;s riser straps. An electronic circuit in the mechanism initiates the separation of a first riser strap to dump the entrained water and next, the second riser to completely sever the chute from the array.

United States Patent [1 1 Johnson Dec. 16, 1975 DEEP OCEAN PARACHUTERELEASE Norman F. Johnson, San Diego, Calif.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC

22 Filed: Mar.3, 1975 21 Appl. No.2 555,012

[75] Inventor:

[52] US. Cl 114/209; 83/39; 114/235 B;

244/151 B; 307/252 N; 307/252 .1; 340/3 T [51] Int. C1. B63B 21/48 [58]Field of Search 114/209, 221 A, 235 B;

244/150, 151 B; 83/39, 639; 307/252 N, 252 J, 236, 305; 340/3 T, 7 PC[56] References Cited UNITED STATES PATENTS 2,536,682 1/1951 Frieder eta1. 114/209 3,298,347 1/1967 Swain et a1 114/235 B 3,382,377 5/1968Huffman et a1 307/236 3,484,626 12/1969 Grafham 307/305 3,616,71711/1971 Jones 114/221 A 3,774,870 ll/l973 Sheffield et a1. 7. 244/151 B3,800,271 3/1974 Stillman 340/7 PC Primary Examiner-Trygve M. BlixAssistant ExaminerCharles E. Frankfort Attorney, Agent, or FirmRichardS. Sciascia; Ervin F. Johnston; William T. Skeer [57] ABSTRACT A droguechute is used to extend a long line transducer array in the water as itis being towed in or played out in an ocean current To avoid problemsduring a subsequent retrieval of the array, the drogue chute isdisconnected. For this reason a release mechanism is interposed betweenthe transducer array and the chute. This release mechanism provides fora nonabrupt separation of the array from the chutes riser straps. Anelectronic circuit in the mechanism initiates the separation of a firstriser strap to dump the entrained water and next, the second riser tocompletely sever the chute from the array.

6 Claims, 5 Drawing Figures US. Pltfiflt Dec. 16, 1975 Sheet 1 of 2 DEEPOCEAN PARACHUTE RELEASE STATEMENT OF GOVERNMENT INTEREST The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Usually, hose-like transducer arrays areconnected to a drogue chute to extend the array to its full length. Whenthe array is. to be deployed, the supporting ship continues to proceedunderway and the drogue chute is cast over the side. The drogue chutefills with water and tows the array from its spool and the array trailsbehind the ship. The chute also holds the array extended when thesupporting craft is at anchor or on-station since the chute will exert adrag in the oceans currents. Thus, it can be seen that a drogue chutecan expedite the deployment and positioning of an elongate array.However, during retrieval of the array, the chutes drag becomesexcessive. Usually, the chute is considered expendable and it is'disconnected by some interposed mechanism. Unfortunately, when thedisconnect would be initiated, a rubber-band-like snap would reboundalong the arrays length. The relatively fragile transducers andelectronics will become damaged and impair the arrays operability. Evenwith a static array, i.e., one not being towed, a certain amount oftension exists along the array between a drogue chute and the anchorpoint. Here again, severing the drogue chute snaps the array. There is'acontinuing need in the state of the art for a drogue chute releasemechanism which avoids snapping the array and the consequent damage.

SUMMARY OF THE INVENTION This invention is directed to providing anapparatus for releasing a drogue chute from an elongate array extendedin tension. A cylindrical housing is connected to the array and a pairof frangible links couple the other end of the housing to the two riserstraps of a drogue chute. A pair of guillotine cable cutters, eachassociated with a separate link, are sequentially initiated first todump the entrained water mass and secondly to separate the drogue chutefrom the array in a two step operation.

It is an object of the invention to provide an improved release for adrogue chute.

Another object is to provide a releasing apparatus for initiating a twostep release of a drogue chute.

Yet another object is to provide a drogue chute release which does notoverly contribute to flow noise.

Yet another object is to provide a fail safe sequential chute releasewhich requires a signal of a first polarity to separate one frangiblelink and a signal of the opposite polarity to separate the otherfrangible link.

These and other objects of the invention will become more readilyapparent from the ensuing specification when taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric depiction ofthe invention linking a drogue chute to an elongate array. 1

FIG. 2 is an enlarged isometric view of the invention.

FIG. 3 is a cross-sectional representation of the invention takengenerally along lines 3-3 in FIG. 2.

FIG. 4 is an isometric view of a detail of the invention.

FIG. 5 is a schematic diagram of the initiation circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, arepresentative embodiment of a hose-like transducer array 10 reachesfrom a surface craft 11 and is held extended by a drogue chute 12.Although the array is shown being deployed from a surface craft, othermodes of operation can dictate that the array be deployed by asubmersible or be trailed from a buoy in the ocean s currents. In anyevent, a drogue chute is connected at the distal end to act as a drag toextend the array as it is pulled through the water or as it streams in acurrent. This type of an arrangement provides more satisfactoryrepresentations of transmitted and received acoustic energy. Arrays thatare allowed to flutter or drift into contorted shape leave much to bedesired when signals are to be analyzed.

Usually, the long line array is stored on a large spool. Unwinding thespool releases the array and an attached drogue chute is released. Asthe chute fills with water, it entrains a water mass and pulls the arrayin a straight line configuration.

However, a retrieval of the drogue chute does pose some problems. Thechute resists being reeled in and the excessive tensile drag may damagethe array. In addition, the chute does not lend itself to being pulledthrough sheaves nor to being wound on the spool.

The solution is to sever the drogue chute from the array by a suitablerelease mechanism and reel in the array. Yet, because the array is heldin tension, severing the chute snaps the array. Particularly, when thearray is hundreds or thousands of feet long, this shock can be quitesevere. Previous trials have demonstrated that the transducer elementsand the associated electronics are damaged during separation.

This invention, a deep ocean drogue release 13, reduces the possibilityof, damaging the array during drogue chute disconnect. The drogue chuterelease mechanism is coupled to two risers 14 extending from droguechute 12 by a pair of swivels 15. The opposite end of the releasemechanism is connected to the array by four cables 16, only three ofwhich are shown in FIG. 3. These cables normally are contained withinthe array and serve as linking strength members among the transducerelements and the associated electronics.

The release mechanism includes a cylindrically shaped housing 17 whichhas substantially the same diameter as the array. Such dimensioningprovides a cleaner hydrodynamic shape and reduces the problemsassociated with excessive flow noise.

The interior of the housing is divided into two cavities 18 and 19 by aseparating wall 20. The housing, separating wall and most of the otherelements to be discussed are fabricated from a corrosion resistantmaterial such as stainless steel, which possess the strength to beartensile loads. Cavity 18 faces the trailing end of the transducer arrayand is closed by a disc-shaped plug 21.

The outside surface of the plug is shaped with four projections 22 whichreceive the four cables 16 mentioned above, to join the drogue releaseto the array. The circumferential surface of the plug is provided withan annular groove 23 carrying an O-ring 24 to seal cavity 18 from thesurroundings. A snap ring 25 fits into an appropriately shaped groove 26in the cylindrically shaped housing to hold the plug in place.

An electronic detonation-initiation circuit 27 is dis posed inwardly ofthe plug and within the confines of cavity 18. The details of thecircuit will be discussed later, however it should be noted that only asingle pair of leads 28 and 28" reach from the electronic circuit to thearray via a packing member 29.

At the opposite end of the housing a round mounting plate 30 carryingO-ring 31 seals shut a cavity 19. Into the cavity a pair of frangiblelinks 32 reach across from appropriately shaped holes 33 in the mountingplate. O-rings encircle the links shanks to keep water out of thehousing interior.

The links are shaped with threaded inner ends 34 for engagingcorrespondingly shaped threads provided in tapped holes 20a inseparating wall 20. The opposite end of each of the frangible links isprovided with a threaded recess 35 which mates with correspondinglythreaded portions 15a of a ring bolt-swivel combination 15. Thus, thedrogue chute is connected to the array via frangible links 32 andhousing 17.

Inside cavity 19 a pair of guillotine cutters 36 are sup ported by apair of nylon clips 37 affixed to the inner surface of mounting plate30. The cutters are of the type manufactured by I-Iolex, Incorporated,I-Iollister, California, under the code identification number 10640.These cutters are initiated to drive a blade against an anvil and toeffect a cutting of a cable placed upon the anvil when a potential isapplied to its pair of leads 39.

The guillotine cutters are so arranged on their clips to align smallerdiametered portions 38 of the frangible links with the blades of each ofthe cutters. The smaller diameter portions were machined down to have atensile strength of about 2,500 pounds. The smaller diametered portionsalso serve as the weak link in the array and will separate first if someunforeseen excessive force is exerted on the array. The Holex 10640cutter is sufficient to break the smaller diameter portion. Both pairsof leads 39 are fed through an opening 20b in wall 20 and are coupled tooutput terminals on the electronic circuit 27.

Part of the essence of this invention resides in the fact that theelectronic circuit is initiated twice by signals of opposite polaritiesacross input leads 28 and 28". A signal of one polarity of the inputsignal actuates one of the guillotine cutters and its associatedfrangible link is severed. One of the risers 14 is released and thedrogue chute slowly dumps its load of entrained water. After apredetermined time, a signal of opposite polarity is fed to electroniccircuit 27 via leads 28 and 28" and the other cutter is actuated. Thesecond actuation severs the other frangible link and the drogue chute isreleased. By this one-two sequence of cutter initiation there is a newtwo step release of the drogue chute. There is no sudden snapping of thearray, but rather a smooth, two-step removal of the drogues drag. Themechanics of this two-step initiation will become more apparent by acloser look at FIG. 5.

Two identical circuits isolated by diodes 40 and 41 are used to fire thetwo cutters independently via only two input leads 28. Apply onepolarity across leads 28' and 28" fires one circuit while reversing thepolarity of the signal fires the other circuit.

When a positive potential is applied to lead 28' a firing capacitor 42begins to charge exponentially through diode 41 at a rate determined bythe line resistances of leads 28" and 28' and the value of firingcapacitor 42. Diode 40 now isolates firing capacitor 43 and itsassociated circuitry. When the potential on firing capacitor 42 reachesa magnitude as determined by a voltage divider network formed byresistor 44 and 45, silicone unilateral switch 46 triggers a siliconcontrolled rectifier 47. This dumps the firing charge stored on firingcapacitor 42 to squib 36a of guillotine cutter 36 to fire it.

Applying a positive potential to lead 28" causes the detonation of theother squib 36a in exactly the same manner. A charge begins toexponentially accumulate on firing capacitor 43 at a rate determined bythe line resistances of line 28 and 28" and the value of firingcapacitor 43. Diode 41 isolates firing capacitor 42 and its associatedcircuitry. As the potential on firing capacitor 43 reaches a magnitudeas determined by a voltage divider network made up of resistors 48 and49, silicone unilateral switch 50 triggers a silicone controlledrectifier 51. This dumps the charge stored on firing capacitor 43through squib 36a to effect its detonation.

The line resistance of the array used in conjunction with this releasemechanism is such that the firing signal need be applied to one of theassociated firing capacitors 42 or 43 for approximately 4 seconds.During this period the accumulated charge reaches a potential on eitherfiring capacitor which is of a sufficient magnitude to actuate itsassociated transistor 46 or 50. This time delay provides an added safetyfeature to prevent accidental firing since it is necessary to apply thefiring signal continuously for 4 seconds before either squib isdetonated.

A pair of resistors 52 and 53 are protective devices for firingcapacitors 42 and 43, respectively. Since the cavity 18 inside ofcylindrically shaped housing 17 is small, the size of the componentsmust be kept down. To help accomplish this all the capacitors chosen areof low voltage ratings. If, for some reason the firing signal wereapplied across terminals 28' and 28" when the connections to the cutterswere inadvertently open, the corresponding charge built on either of thefiring capacitors 42 and 43 would not reach high enough levels to damagethem. Thus, the resistors 52 and 53 are included to provide a path todischarge the firing capacitors.

As a final step to ensuring the efficient operation of theaforedescribed electronic circuit, it was fabricated on a printedcircuit board and potted in an epoxy-like block sized to fit withincavity 18.

Obviously, many modifications and variations are possible in the lightof the above teachings, and it is therefore understood that theinvention may be practiced otherwise than as specifically described.

What is claimed is:

1. An apparatus for releasing a drogue chute from an elongate arrayextended in tension comprising:

a housing connected to the array;

means for frangibly coupling the housing to more than one riser of thedrogue chute;

means for breaking the frangible coupling means being mounted adjacentthereto; and

means for sequentially initiating the breaking means to effect releasingof the drogue chute in stages thereby preventing the snapping of theelongate array.

2. An apparatus according to claim 1 in which the frangible couplingmeans are a pair of alloy links each secured to a separate riser and thebreaking means are a pair of guillotine cutters each provided with anopening for receiving a separate alloy link therethrough.

3. An apparatus according to claim 2 in which the sequentiallyinitiating means is an electronic circuit formed of components whichinitiate the detonation of one of the guillotine cutters when anactuation signal of one polarity is fed to it and which initiate thedetonation of the other guillotine cutter when an actuation signal ofthe reverse polarity is fed to it.

4. An apparatus according to claim 3 in which the electronic circuitincludes a charging and firing capacitor coupled to each guillotinecutter to provide a delay between the time the actuation signal is fedto the electronic circuit and a guillotine cutter is detonated.

5. An apparatus according to claim 4 in which both guillotine cuttersare orthogonally disposed with respect to their associated alloy link toassure the releasing of the drogue chute.

6. An apparatus according to'claim 5 in which the housing iscylindrically shaped having an outer diameter the same as the array toreduce the problems associated with excessive low noise.

1. An apparatus for releasing a drogue chute from an elongate arrayextended in tension comprising: a housing connected to the array; meansfor frangibly coupling the housing to more than one riser of the droguechute; means for breaking the frangible coupling means being mountedadjacent thereto; and means for sequentially initiating the breakingmeans to effect releasing of the drogue chute in stages therebypreventing the snapping of the elongate array.
 2. An apparatus accordingto claim 1 in which the frangible coupling means are a pair of alloylinks each secured to a separate riser and the breaking means are a pairof guillotine cutters each provided with an opening for receiving aseparate alloy link therethrough.
 3. An apparatus according to claim 2in which the sequentially initiating means is an electronic circuitformed of components which initiate the detonation of one of theguillotine cutters when an actuation signal of one polarity is fed to itand which initiate the detonation of the other guillotine cutter when anactuation signal of the reverse polarity is fed to it.
 4. An apparatusaccording to claim 3 in which the electronic circuit includes a chargingand firing capacitor coupled to each guillotine cutter to provide adelay between the time the actuation signal is fed to the electroniccircuit and a guillotine cutter is detonated.
 5. An apparaTus accordingto claim 4 in which both guillotine cutters are orthogonally disposedwith respect to their associated alloy link to assure the releasing ofthe drogue chute.
 6. An apparatus according to claim 5 in which thehousing is cylindrically shaped having an outer diameter the same as thearray to reduce the problems associated with excessive low noise.